/*

File: Calendar.m

Abstract: Model of a calendar.

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*/ 

/*

 *  Calendar is the "model" object of a calendar that manages CalEvent objects. 

 *  The Calendar object fetches CalEvent objects, applies changes from iCal to 

 *  local CalEvent objects, and saves user changes to CalEvent objects.

 */

#import "Calendar.h"

#import <CalendarStore/CalendarStore.h>

@implementation Calendar

- (id)init

{

    self = [super init];

    if (self) {

        // Add the receiver as an observer of Calendar Store notifications

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(eventsChanged:) 

            name:CalEventsChangedExternallyNotification object:[CalCalendarStore defaultCalendarStore]];

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(eventsChanged:) 

            name:CalEventsChangedNotification object:[CalCalendarStore defaultCalendarStore]];

        // Create a predicate to use to fetch the events

        NSInteger year = [[NSCalendarDate date] yearOfCommonEra];

        startDate = [[NSCalendarDate dateWithYear:year month:1 day:1 hour:0 minute:0 second:0 timeZone:nil] retain]; 

        endDate = [[NSCalendarDate dateWithYear:year month:12 day:31 hour:23 minute:59 second:59 timeZone:nil] retain]; 

        NSPredicate *eventsForThisYear = [NSPredicate eventPredicateWithStartDate:startDate endDate:endDate 

           calendars:[[CalCalendarStore defaultCalendarStore] calendars]];

        // Fetch all events for the current year

        events = [[NSMutableArray array] retain];

        [self addEventArray:[[CalCalendarStore defaultCalendarStore] eventsWithPredicate:eventsForThisYear]];

    }

    return self;

}

- (void)dealloc

{

    // Remove the receiver as an observer of Calendar Store notifications

    [[NSNotificationCenter defaultCenter] removeObserver:self 

        name:CalEventsChangedExternallyNotification object:[CalCalendarStore defaultCalendarStore]];

    [[NSNotificationCenter defaultCenter] removeObserver:self 

        name:CalEventsChangedNotification object:[CalCalendarStore defaultCalendarStore]];

    [events release];

    [startDate release];

    [endDate release];

    [super dealloc];

}

// Returns the receiver's events.

- (NSMutableArray *)events

{

    return events;

}

// Adds an array of events to the calendar. Uses mutableArrayValueForKey: so changes 

// made locally are updated in the UI via KVO and Cocoa Bindings. Also, adds the

// receiver as an observer of changes to all events. This is needed to save local changes

// to Calendar Store.

- (void)addEventArray:(NSArray *)someEvents

{

    NSEnumerator *eventEnumerator = [someEvents objectEnumerator];

    id event;

    while (event = [eventEnumerator nextObject]){

        // Observe changes to the start and end dates

        [event addObserver:self forKeyPath:@"startDate"

                   options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) 

                   context:NULL];

        [event addObserver:self forKeyPath:@"endDate"

                   options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) 

                   context:NULL];

        [event addObserver:self forKeyPath:@"title"

                   options:(NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld) 

                   context:NULL];

    }

    // This triggers KVO messages to CalendarController

    [[self mutableArrayValueForKey:@"events"] addObjectsFromArray:someEvents];

}

// Removes an array of events from the calendar. Uses mutableArrayValueForKey: so changes 

// made locally are updated in the UI via KVO and Cocoa Bindings. Also removes the receiver

// as an observer of the removed events.

- (void)removeEventArray:(NSArray *)someEvents

{

    NSEnumerator *eventEnumerator = [someEvents objectEnumerator];

    id event;

    while (event = [eventEnumerator nextObject]){

        [event removeObserver:self forKeyPath:@"startDate"];

        [event removeObserver:self forKeyPath:@"endDate"];

        [event removeObserver:self forKeyPath:@"title"];

    }

    // This triggers KVO messages to CalendarController

    [[self mutableArrayValueForKey:@"events"] removeObjectsInArray:someEvents];

}

// Catch and update changes made to records externally. Uses addEvents: and removeEvents: that 

// triggers updates to the UI via KVO and Cocoa Bindings.

- (void)eventsChanged:(NSNotification *)notification 

{

    NSLog(@"Invoking eventsChanged:...");

    // Apply delete changes to the events array.

    NSArray *deletedRecords = [[notification userInfo] valueForKey:CalDeletedRecordsKey];

    if (deletedRecords != nil){

        NSLog(@"Removing events from Calendar model deletedRecords=%@", [deletedRecords description]);

        // Find the local CalEvent objects to delete by matching the UIDs.

        NSEnumerator *uidEnumerator = [deletedRecords objectEnumerator];

        NSString *uid;

        NSPredicate *uidPredicate;

        NSArray *filteredEvents;

        NSMutableArray *someEvents = [NSMutableArray array];

        while (uid = [uidEnumerator nextObject]){

            uidPredicate = [NSPredicate predicateWithFormat:@"uid like %@", uid];

            filteredEvents = [events filteredArrayUsingPredicate:uidPredicate];

            if (filteredEvents != nil)

                [someEvents addObjectsFromArray:filteredEvents];

            else

                NSLog(@"   Can't find event for uid=%@", uid);

        }

        // This triggers KVO messages to CalendarController

        [self removeEventArray:someEvents];

    }

    // Apply insert changes to the events array.

    NSArray *insertedRecords = [[notification userInfo] valueForKey:CalInsertedRecordsKey];

    if (insertedRecords != nil){

        NSLog(@"Adding events to Calendar model insertedRecords=%@", [insertedRecords description]);

        // Create an array containing the CalEvent objects to add. Transforms the UIDs to CalEvent objects.

        NSEnumerator *uidEnumerator = [insertedRecords objectEnumerator];

        NSString *uid;

        NSMutableArray *someEvents = [NSMutableArray array];

        while (uid = [uidEnumerator nextObject]){

            // Since recurring events have the same UIDs, create a predicate that will fetch all events belonging to a

            // recurrence.

            NSPredicate *uidPredicate = [NSPredicate eventPredicateWithStartDate:startDate endDate:endDate UID:uid

                calendars:[[CalCalendarStore defaultCalendarStore] calendars]];

            NSArray *filteredEvents = [[CalCalendarStore defaultCalendarStore] eventsWithPredicate:uidPredicate];

            if (filteredEvents != nil)

                [someEvents addObjectsFromArray:filteredEvents];

            else

                NSLog(@"   Can't find any remote events for uid=%@", uid);

        }

        // This triggers KVO messages to CalendarController

        [self addEventArray:someEvents];

    }

    // Apply update changes to event properites.

    NSArray *updatedRecords = [[notification userInfo] valueForKey:CalUpdatedRecordsKey];

    if (updatedRecords != nil){

        NSLog(@"Updating events in Calendar model... updatedRecords=%@", [updatedRecords description]);

        // Currently, you need to delete and add the changed event.

        // Create an array containing the local CalEvent objects to update.

        // Finds the local CalEvent objects in the events array that have

        // the same UIDs.

        NSEnumerator *uidEnumerator = [updatedRecords objectEnumerator];

        NSString *uid;

        NSPredicate *uidPredicate;

        NSArray *filteredEvents;

        NSMutableArray *oldEvents = [NSMutableArray array], *newEvents = [NSMutableArray array];

        while (uid = [uidEnumerator nextObject]){

            uidPredicate = [NSPredicate predicateWithFormat:@"uid like %@", uid];

            filteredEvents = [events filteredArrayUsingPredicate:uidPredicate];

            if (filteredEvents != nil)

                [oldEvents addObjectsFromArray:filteredEvents];

            else

                NSLog(@"   Can't find any local events for uid=%@", uid);

        }

        // This triggers KVO messages to CalendarController

        //NSLog(@".... removing oldEvents=%@", [oldEvents description]);

        [self removeEventArray:oldEvents];

        // Create an array containing the new CalEvent objects to add. Transforms UIDs to CalEvent objects.

        uidEnumerator = [updatedRecords objectEnumerator];      

        while (uid = [uidEnumerator nextObject]){

            // Since recurring events have the same UIDs, create a predicate that will fetch all events belonging to a

            // recurrence.

            NSPredicate *uidPredicate = [NSPredicate eventPredicateWithStartDate:startDate endDate:endDate UID:uid

                calendars:[[CalCalendarStore defaultCalendarStore] calendars]];

            NSArray *filteredEvents = [[CalCalendarStore defaultCalendarStore] eventsWithPredicate:uidPredicate];

            if (filteredEvents != nil)

                [newEvents addObjectsFromArray:filteredEvents];

            else

                NSLog(@"   Can't find any remote events for uid=%@", uid);

        }

        // This triggers KVO messages to CalendarController

        //NSLog(@".... adding newEvents=%@", [newEvents description]);

        [self addEventArray:newEvents];

    }

    return;

}

// KVO Methods

// Applies local changes to CalEvent object properties by the UI and saves them to Calendar Store.

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context

{   

    NSLog(@"observeValueForKeyPath:... keyPath=%@", keyPath);   

    // A property of a record changed

    if ([object isKindOfClass:[CalEvent class]] && ([[change valueForKey:NSKeyValueChangeKindKey] intValue] == NSKeyValueChangeSetting)){

        NSLog(@"The UI or the calendar model (originated by iCal) changed a CalEvent property...");

        // Need to differentiate UI changes from iCal changes so iCal changes are not pushed back to iCal (at the moment Calendar

        // is not applying individual changes so this method is only invoked when the UI changed a property).

        // Tempararily, remove the receiver as an observer of Calendar Store notifications

        // (Otherwise, saving the changes will trigger a local update to the same record.)

        [[NSNotificationCenter defaultCenter] removeObserver:self 

            name:CalEventsChangedExternallyNotification object:[CalCalendarStore defaultCalendarStore]];

        [[NSNotificationCenter defaultCenter] removeObserver:self 

            name:CalEventsChangedNotification object:[CalCalendarStore defaultCalendarStore]];

        // Save the change to Calendar Store.

        [[CalCalendarStore defaultCalendarStore] saveEvent:object span:CalSpanThisEvent];

        // Add the receiver as an observer of Calendar Store notifications

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(eventsChanged:) 

            name:CalEventsChangedExternallyNotification object:[CalCalendarStore defaultCalendarStore]];

        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(eventsChanged:) 

            name:CalEventsChangedNotification object:[CalCalendarStore defaultCalendarStore]];

    }   

    return;

}

@end